Vitamins and Minerals: How Much Should You Take?

Vitamins and Minerals: How Much Should You Take?

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How much of a vitamin or mineral supplement should you take? Are your daily multivitamins enough, or should you worry about vitamin deficiency? Could you already be taking too much? It can be hard to tell -- especially with so many nutritional terms, abbreviations, and numbers out there. Here’s what you need to know.

To help people better understand the minimum and maximum doses for supplements, the Institute of Medicine has established some guidelines.
  • The RDA (Recommended Dietary Allowance) and the AI (Adequate Intake) are the amounts of a vitamin or mineral you need to stay healthy and avoid nutritional deficiencies. They are tailored to women, men, and specific age groups.
  • The UL (Tolerable Upper Intake Level) is the maximum amount of daily vitamins and minerals that you can safely take without risking an overdose or serious side effects. For certain nutrients, the higher you go above the UL, the greater the chance of having problems.
Separate from the RDA and the UL, the FDA uses a different measurement of nutritional intake.
  • The DV (Daily Value) is the only measurement you’ll find on food and supplement labels. That’s because space is limited, and there’s a need for one single reference number. That number is the amount of a vitamin or nutrient that a person should get for optimum health from a 2,000 calories-a-day diet. The DV is sometimes the same as the RDA and sometimes not.
Although the details may be different, just remember that the RDA and DV are both designed to help us get the nutrients we need to prevent disease and avoid problems caused by malnutrition.
But many people take higher doses of specific supplements in the hopes of gaining other health benefits, like added protection against or treatment of disease.
Is taking doses higher than the RDA or DV safe? For many vitamins and minerals, yes. In some cases, doctors even recommend it. Take vitamin D, for instance. The RDA of vitamin D for a 60-year-old is 600 international units (IU). But for bone health, the National Osteoporosis Foundation recommends 800-1,000 IU for that age group.

Table: RDAs and ULs for Vitamins and Minerals

The Institute of Medicine has determined upper limits for 24 nutrients. Here is a chart comparing the RDA and UL for all of them.

This table only applies to adults age 19 or older. It also does not apply to women who are pregnant or breastfeeding, because they have different nutritional requirements.

Anyone who is under 19, pregnant, or breastfeeding should check with a doctor before using supplements.

Vitamin
or Mineral
Recommended Dietary Allowance (RDA) or Adequate Intake (AI)
Nutrients with AIs are marked with an (*)
Upper Tolerable Limit (UL)
The highest amount you can take without risk
Boron
Not determined.
20 mg/day
Calcium
  • Age 1-3: 700 mg/day
  • Age 4-8: 1,000 mg/day
  • Age 9-18: 1,300 mg/day
  • Age 19-50: 1,000 mg/day
  • Women age 51+: 1,200 mg/day
  • Men age 71+: 1,200 mg/day
  • Age19-50: 2,500 mg/day 
  • Age 51 and up:2,000 mg/day
Chloride
  • Age 19-50: 2,300 mg/day
  • Age 50-70: 2,000 mg/day
  • Age 70 and older: 1,800 mg/day
3,600 mg/day
Choline
(Vitamin B complex)
  • Age 70 and older: 1,800 mg/day
  • Women: 425 mg/day *
3,500 mg/day
Copper
900 micrograms/day
10,000 micrograms/day
Fluoride
  • Men: 4 mg/day *
  • Women: 3 mg/day *
10 mg/day
Folic Acid (Folate)
400 micrograms/day
1,000 micrograms/day

This applies only to synthetic folic acid in supplements or fortified foods. There is no upper limit for folic acid from natural sources.
Iodine
150 micrograms/day
1,100 micrograms/day
Iron
  • Men: 8 mg/day
  • Women age 19-50: 18 mg/day
  • Women age 51 and up: 8 mg/day
45 mg/day
Magnesium
  • Men age 19-30: 400 mg/day
  • Men age 31 and up: 420 mg/day
  • Women age 19-30: 310 mg/day
  • Women age 31 and up: 320 mg/day
350 mg/day
This applies only to magnesium in supplements or fortified foods. There is no upper limit for magnesium in food and water.
Manganese
  • Men: 2.3 mg/day *
  • Women: 1.8 mg/day*
11 mg/day
Molybdenum
45 micrograms/day
2,000 micrograms/day
Nickel
Not determined
1.0 mg/day
Phosphorus
700 mg/day
Up to age 70: 4,000 mg/day Over age 70: 3,000 mg/day
Selenium
55 micrograms/day
400 micrograms/day
Sodium
  • Age 19-50: 1,500 mg/day
  • Age 51-70: 1,300 mg/day
  • Age 71 and up: 1,200 mg/day
2,300 mg/day
Vanadium
Not determined
1.8 mg/day
Vitamin A
  • Men: 3,000 IU/day
  • Women: 2,310 IU/day
10,000 IU/day
Vitamin B3 (Niacin)
  • Men: 16 mg/day
  • Women: 14 mg/day
35 mg/day
This applies only to niacin in supplements or fortified foods. There is no upper limit for niacin in natural sources.
Vitamin B6
  • Men age 19-50: 1.3 mg/day
  •  Men age 51 up:1.7 mg/day
  •  Women age 19-50: 1.3 mg/day
  •  Women age 51 up: 1.5 mg/day
100 mg/day
Vitamin C
  • Men: 90 mg/day
  • Women: 75 mg/day
2,000 mg/day
Vitamin D (Calciferol)
  • Age 1-70: 15 micrograms/day
    (600 IU, or international units) *
  • Age 70 and older: 20 micrograms/day
    (800 IU) *
100 micrograms/day
(4,000 IU)
Vitamin E
(alpha-tocopherol)
22.4 IU/day
1,500 IU/day

This applies only to vitamin E in supplements or fortified foods. There is no upper limit for vitamin E from natural sources.
Zinc
  • Men: 11 mg/day
  • Women: 8 mg/day
40 mg/day

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